<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>可见</title>
  <link rel="stylesheet" href="../../bom/css/base.css">
  <style>
    .dv {
      margin: calc(100vh + 20px) 0px;
      width: 50vw;
      height: 200px;
      background-color: pink;
    }
  </style>
</head>

<body>
  <div class="dv"></div>
</body>
<script>
  "use strict";
  const observer = new IntersectionObserver((entires, observer) => {

  });
</script>

</html>